Speaking-telephone



3 Sheets-Sheet 1.

E. GRAY.

Speaking Telephone.

- No. 233,344. Patented Oct. 19, 1880.

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3 sheets sheet 2.

E. GRAY. Speaking Telephone.

No. 233,344. Patented Oct. 19,1880.

WITNESSES g IJVVENTOR %l y. Elm/Ea, Gray By his .dttorneys BM WLQQ- m, PNONUTMOGRAPHER. WASNIHGTDN. D Q

E. GRAY.

3Sheets--Sheet 3.

Speaking Telephone.

Patented Oct. 19,1880.

I. V VEXTOR Elisha, Gray. By his .dtfm'm'ys N PETER8. PNO

H MPH, WISHIIGTON. D. C-

UNITED, STATES PATENT OFFICE.

ELISHA GRAY, OF CHICAGO, ILLINOIS.

SPEAKING-TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 233,344, dated October 19, 1880.

Application filed May 13, 1878.

To all whom it may concern:

Be it known that I, ELISHA GRAY, a citizen of the United States, and a resident of Ohicago, in the county of (look and State of Illinois, have invented new and useful Improvements in Speaking-Telephones, of which the following is a specification.

My present invention more especially relates to and constitutes an improvement upon my bipolar telephone, for which an application for Letters Patent of the United States was filed by me March 21, 1878, upon which Letters Patent No. 204,029 were granted May 21, 1876, and upon my duplex bipolar telephone filed May 3, 1878.

The object of my present improvement is, while preserving the portable feature of the instrument, (so as to enable it to be handled with facility,) to secure an increased volume and elearness of sound, which ends I attain by combining a series of duplex bipolar telephones with proper circuit-connections, and witha common mouthpiece, around which they are arranged.

The subject-matter claimed hereinafter specifically will be designated.

The accompanying drawings represent so much of my improved m ultipolar telephone as is necessary to illustrate the subject-matter herein claimed as constructed in the best way now known to me. Its details of construction and arrangement may, however, be varied in various ways Without departing from the spirit of my invention, and some ofthe improvements may be used without the others in telephones of different construction.

Figure 1 represents a plan or top view of a multiplex bipolar telephone composed of two duplex bipolar telephones, and having four pairs of diaphragms arranged around a common mouth-piece, each diaphragm having its own magnet and each set or pair of diaphragms being mounted on one pole of a permanent magnet. Fig. 2 represents a side elevation thereof, partly in central longitudinal section therethrough, on the line 2 2 of Fig. 1. Fig. 3 represents a view similar to that shown in the preceding figure of an instrument, having each pair of diaphragms -mounted on its respective permanent magnet. Fig. 4 shows the arrangement of the circuit-connections.

My improved apparatus embodies all that is shown in my bipolar and duplex bipolar telephones hereinbefore mentioned in duplicate, having in the instrument shown in Figs. 1 and 2 two permanent U-shaped or horseshoe steel magnets, A, arranged at right angles to each other, constituting the handle of the instrument, rubber disks B B, helices O 0, softiron cores D D, diaphragms E E, screw-caps F F, clamping-rings G, and a common mouthpiece, H, terminating at the junction of four branch tubes, h, each branch being secured to its respective cap so as to bring its mouth opposite the center of its respective diaphragm.

A tubular soft-iron core, D, extends through the poles of each permanent magnet far enough to receive a supplementary helix, 0. In front of this electro-magnet is mounted a secondary diaphragm, E, in precisely the same manner as the corresponding one, E. The arrangement of the magnet and diaphragm relatively to the pole is, however, reversed.

1 The secondary cap F is made solid, with no opening for the mouth-piece.

The core D has a small hole drilled through it from end to end, about one-eighth of an inch in diameter. In this hole is suspended a light rod, d, of wood or some non-magnetic metal, (such as brass, for instance,) each end of which rod is attached to its respective diaphragm E E, so that the movement of one, from any cause whatever, produces a corresponding movement in the other.

The diaphragms, it will be observed, are mounted in pairs upon the poles of the permanent magnets, which magnets, under the arrangement shown in Figs. 1 and 2, are arranged transversely to each other to constitute the handle or support of the instrument, and'are secured at their neutral axis or point of junction by suitable fastenings. The diaphragms are likewise arranged around the mouth-piece, the edges of the inner ones of each set nearly touching, and with their surfaces inclined at an angle of about sixty degrees with reference to the one opposite, by which means the lips of the speaker are brought close to all the inner diaphragms, and so that practically each diaphragm is actuated with the same electromotive force or energy as a single one constructed in the ordinary way would be, by

which means I am enabled to generate almost eight times the electro-motive force that a single diaphragm would produce. In consequence of this organization articulate words are trans- 5 mitted with much greater force and clearness than they are with a smaller number of diaphragms under the same circumstances.

The obvious advantage of my improvement is that I am enabled, under the organization 0 parts above described, to vibrate two diaphragms in front of each pair of electro-magnets, both of which magnets are charged from the same pole of a permanent magnet. Experience has demonstrated that this method will generate much greater electrical force than a single diaphragm, and consequently produce a much louder sound.

A similar apparatus to that above described is attached to each pole of the magnets, and

I am thus enabled to vibrate eight diaphragms, instead of four, as in my multipolar telephone, and still maintain the same relations between the diaphragm and mouth piece as in the aforesaid instrument, upon which an application for Letters Patent has been filed May 3,

Another mode of producing substantially the same effect as that produced by the rod connecting each pair of diaphragms (at least 0 in kind, it not in degree) is to leave out the connecting-rod, in which case the secondary diaphragm will be actuated by the vibrations of the column of air contained in the hollow core D. It should be observed that this hollow core, in connection with this space between the diaphragms, forms an airtight chamber. The solid cap and secondary diaphragm also constitutes a closed chamber.

The several electro-magnets in the system are connected to line either tandem or joint, as the resistance of the line upon which the instrument is used requires.

A battery and circuit arrangement similar to either of those shown in my respective ap- 5 plications of October 29, 1877, Case 1, or Jauuary 17, 1878, may be used.

In Fig. 3 the circuit is shown as including all the helices in succession or tandem.

Instead of mounting each pair of electromagnets and diaphragms on a single pole of the permanent magnets, as shown in Figs. 1, 2, each pair may be mounted on a separate magnet, as shown in Fig. 3. It follows as a consequence of this arrangement, however,

that twice as many permanent magnets are needed to operate a given number of diaphragms as would be required in the instrument shown in Figs. 1 and 2. The space between the two poles of the permanent magnet shown in Fig. 3 is bridged over with a tubular piece, I, of brass or some non-magnetic substance. This is to confine the column of air contained in the casing and core of the magnets.

In other respects the apparatus is substantially the same as that hereinbefore described.

The operation of my improved telephone will readily be understood from the foregoing description.

I do not broadly claim herein the combination of four single telephones with a common mouth-piece, or the duplex arrangement of each set of diaphragms relatively to a permanent magnet; nor do I claim the details of construction of the devices herein shown, it being my intention to limit my present claims to the organizations incident to combining a series of duplex telephones with a common mouth-piece, the other matters hereinbet'ore set forth constituting the subject-matter of other applications for Letters Patent filed by 1119.

I claim as of my own invention- 1. The combination, substantially as hereinbefore set forth, of primary and secondary diaphragms mounted in pairs on the poles of the respective permanent magnets-one pair to each pole-the softriron cores and their helices interposed between each pair of diaphragms, circuit-connections, including all the go helices, and a four-branch mouth-piece common to all the primary diaphragms.

2. A multiplex bipolar telephone consistin g of the combination, substantially as hereinbefore set forth, of twoor more permanent 5 magnets, electro-magnets mounted thereon in pairs, primary and secondary diaphragm's arranged in pairs-a diaphragm for each electromagnet-an electric circuit including the he]- ices of all the electro-magnets in succession or too tandem, and a four-branch mouth-piece common to all the primary diaphragms.

In testimony whereof I have hereunto subscribed my name.

ELISHA GRA'Y.

Witnesses A. G. swnnrwour, D. M. ERSKENE, Jr. 

